TY - JOUR

T1 - Where does cosmological perturbation theory break down?

AU - Armendariz-Picon, Cristian

AU - Fontanini, Michele

AU - Penco, Riccardo

AU - Trodden, Mark

PY - 2009

Y1 - 2009

N2 - It is often assumed that initial conditions for the evolution of a cosmological mode should be set at the time its physical wavelength reaches a cut-off of the order of the Planck length. Beyond that scale, trans-Planckian corrections to the dispersion relation are supposed to become dominant, leading to the breakdown of cosmological perturbation theory. In this paper, we apply the effective field theory approach to the coupled metric-inflaton system in order to calculate the corrections to the power spectrum of scalar and tensor perturbations induced by higher-dimension operators at short wavelengths. These corrections can be interpreted as modifications of the dispersion relation, and thus open a window to probe the validity of cosmological perturbation theory. Both for scalars and tensors, the modifications become important when the Hubble parameter is of the order of the Planck mass, or when the physical wave number of a cosmological perturbation mode approaches the square of the Planck mass divided by the Hubble constant. Thus, the cut-off length at which such a breakdown occurs is finite, but much smaller than the Planck length.

AB - It is often assumed that initial conditions for the evolution of a cosmological mode should be set at the time its physical wavelength reaches a cut-off of the order of the Planck length. Beyond that scale, trans-Planckian corrections to the dispersion relation are supposed to become dominant, leading to the breakdown of cosmological perturbation theory. In this paper, we apply the effective field theory approach to the coupled metric-inflaton system in order to calculate the corrections to the power spectrum of scalar and tensor perturbations induced by higher-dimension operators at short wavelengths. These corrections can be interpreted as modifications of the dispersion relation, and thus open a window to probe the validity of cosmological perturbation theory. Both for scalars and tensors, the modifications become important when the Hubble parameter is of the order of the Planck mass, or when the physical wave number of a cosmological perturbation mode approaches the square of the Planck mass divided by the Hubble constant. Thus, the cut-off length at which such a breakdown occurs is finite, but much smaller than the Planck length.

UR - http://www.scopus.com/inward/record.url?scp=70349653361&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=70349653361&partnerID=8YFLogxK

U2 - 10.1088/0264-9381/26/18/185002

DO - 10.1088/0264-9381/26/18/185002

M3 - Article

AN - SCOPUS:70349653361

SN - 0264-9381

VL - 26

JO - Classical and Quantum Gravity

JF - Classical and Quantum Gravity

IS - 18

M1 - 185002

ER -